After an oil drilling rig drills a well and installs the well casing, the rig is dismantled and removed from the site. From that point on, a mobile repair unit, or service rig, is typically used to service the well. Servicing includes, for example, installing and removing inner tubing strings, sucker rods, and pumps. This is generally done with a cable hoist system that includes a traveling block that raises and lowers the aforementioned tubing strings, sucker rods, and pumps.
Conventional systems describe methods for monitoring the movement of a traveling block on a drilling rig. In these conventional systems, the traveling block can be raised or lowered beyond a safe limit. This is called “crown out” if the traveling block goes above its upper-most safe position, and “floor out” if it goes below its lower-most safe is position. Crown out/floor out can result in equipment damage and/or present a hazard to personnel working on the equipment. Because it is often not possible for the operator of the cable hoist system to see the position of the traveling block, or because the operator can be otherwise distracted from the position of the traveling block, the operator can inadvertently exceed safe positions of the traveling block.
Although many conventional methods set out to solve the problem of unsafe hoist operation in an oil drilling rig, many drawbacks still remain when applying the these technologies to a service rig. For instance, in many cases the operator cannot see the block and needs the ability to make decisions based on the where the block is located without actually seeing the block. In addition evaluators, such as supervisors, service rig owners or well owners need a way to evaluate the effectiveness of a rig operator's actions and safety regarding the position of the block during rig operations.
The present invention is directed to evaluating block position from a display of block position data and determining whether to continue raising or lowering the block based on the displayed data. In addition, the present invention is directed to methods for evaluating block position data and encoder velocity data to determine the activities that occurred on the service rig and the speed at which the block was operating on the service rig.